|Year : 2008 | Volume
| Issue : 5 | Page : 556
Pre-Emptive Analgesia for Elective Maxillofacial Surgery Using 0.25% Bupivacaine
Radhika Krishnan1, S Shivananda2, Uma Raman3
1 Associate Professor (Anesthesiology), Ragas Dental College and Hospital, Chennai, India
2 PG. Student, Dept. of Oral and Maxillofacial Surgery, Ragas Dental College and Hospital, Chennai, India
3 HOD, Dept. of Oral and Maxillofacial Surgery Ragas Dental College and Hospital, Chennai, India
|Date of Acceptance||18-Jul-2008|
|Date of Web Publication||19-Mar-2010|
G 203, Atrium, 22, Kalakshetra road, Thiruvanmiyur, Chennai 600041
Source of Support: None, Conflict of Interest: None
The efficacy of 0.25% bupivacaine as a pre-emptive analgesic agent was evaluated in a prospective case control study - a group of patients undergoing elective orthognathic surgery against a matched control group. Bupivacaine was administered as a series of nerve blocks prior to the incision for the surgery. Outcome variables measured were postoperative pain by Visual Analogue Scale (VAS) score, need and amount of rescue analgesics and the incidence of known complications associated with these agents. The VAS score was significantly lower in the group receiving pre-emptive analgesia for upto 40 hours postoperatively, (P<0.05). The amount of rescue analgesics administered and the incidence of complications attributed were less in study group than that of the control group, (P>0.05). Bupivacaine can be used for pre-emptive analgesia in oral and maxillofacial surgery.
Keywords: Pre-emptive analgesia, Bupivacaine, Orthognathic surgery, Preincisional nerve blocks
|How to cite this article:|
Krishnan R, Shivananda S, Raman U. Pre-Emptive Analgesia for Elective Maxillofacial Surgery Using 0.25% Bupivacaine. Indian J Anaesth 2008;52:556
|How to cite this URL:|
Krishnan R, Shivananda S, Raman U. Pre-Emptive Analgesia for Elective Maxillofacial Surgery Using 0.25% Bupivacaine. Indian J Anaesth [serial online] 2008 [cited 2020 Sep 25];52:556. Available from: http://www.ijaweb.org/text.asp?2008/52/5/556/60674
| Introduction|| |
Effective postoperative relief of pain is important not only for humanitarian reasons, but also for physiological benefit. Effective pain relief means a smoother postoperative course with earlier discharge from hospital and prevents the onset of chronic pain syndrome.
The goal of effective postoperative pain management must be to eliminate pain and discomfort with minimum side effects. The method must also be simple, economical and easy to use.
Prevention of postoperative pain can be achieved by:
1. Effective blockade of noxious stimuli generated during surgery - that is after central pain sensitization.
2. Preemptive analgesia or anti nociceptive treatment started before surgery in order to prevent central sensitization and limit the subsequent pain experience. 
Various pre-incisional nerve blocks have beenused as pre-emptive analgesic agents using the long acting local anaesthetic agent bupivacaine. , We have used these techniques in a series of orthognathic surgeries using maxillary and mandibular peripheral nerve blocks to assess the efficacy of 0.25% bupivacaine as a pre-emptive analgesic agent. 
We evaluated the use of preincisional peripheral nerve blocks using 0.25% bupivacaine along with general anaesthesia, compared to conventional general anaesthesia alone for oral& maxillofacial surgical procedures in terms of blocks to be given, postoperative pain relief, requirements of analgesics in the postoperative period, side affects of the drugs used and patient recovery and comfort.
| Methods|| |
Twenty five consecutive patients admitted for elective orthognathic surgery in the Dept. of Oral Maxillofacial Surgery, Ragas Dental College Hospital during the period Dec 2004 to July 2006 were included in the study. Ethical Committee Clearance was obtained for the study. All patients were informed about the nature of the study and their written consent obtained.
All patients were within the age group 18 to 35yrs and were ASA grade I or II. They underwent various procedures such as Le Fort I, anterior maxillary osteotomy in the maxilla and subapical osteotomy, bilateral sagittal split osteotomy and genioplasty in the mandible. The blocks given were infraorbital nerve block  [Figure 1] and [Figure 2] posterior superior alveolar nerve block  [Figure 3] and [Figure 4] and greater palatine nerve block  [Figure 5] and [Figure 6] for the maxillary procedures and mandibular nerve block using the Gow Gates technique  [Figure 7] and [Figure 8] and inferior alveolar nerve block for the mandible  [Figure 9] and [Figure 10] using the anatomical landmarks shown in the figures.
On the day of surgery patients received premedication with pentazocine 30 mg IM, promethaz i ne 25mg and glycopyrrolate 0.2mg IM. The local anaesthetic was tested for allergy. Patients were induced with thiopentone sodium 5mg.kg -1 , suxamethonium 2mg.kg -1 . Nasotracheal intubation was done. Patients were maintained with nitrous oxide, oxygen and 0.5% halothane and incremental doses of vecuronium (0.08mg.kg -1 initial dose followed by 0.02mg.kg -1 as and when required), midazolam(0.02mg.kg -1 every hour) and fentanyl (2mcg.kg -1 every hour)
The study patients were allocated into two groups which were matched for age, sex and type of procedure. In addition they were evaluated for level of anxiety by Corah's anxiety scale.  Those with history of allergy to known anaesthetic or analgesic agents as well as high levels of anxiety were excluded from the study.
The Study group received the pre-emptive analgesic 2 ml of 0.25% bupivacaine in the form of a preincisional nerve block appropriate to the type of surgery to be performed. The Control group was administered a similar injection using normal saline. Both injections were given 10 minutes prior to the planned start of surgery. During the surgical procedures oxygen saturation, ECG, heart rates were monitored continuously and blood pressure recorded every 5 minutes. All patients were extubated using standard criteria after reversal with neostigmine and glycopyrrolate.
| Post operative data collection:|| |
- Pulse rate, blood pressure, respiratory rate recorded every thirty minutes for the first six hours postoperatively
- VAS  recorded every 2, 4, 6, 8, 12, 16, 24,32& 40 hours postoperatively in the surgical ward.
- Incidences of nausea, vomiting, gastric acidity
- Pain at intra muscular injection site
- Symptoms of numbness at surgical site
- Any discomfort associated with paresthesia
| VAS score.|| |
Score 0 no pain
Score 0 to 25 mild pain
Score 25 to 50 moderate pain Score 50 to 75 severe pain Score 75 to 100 very severe pain
Diclofenac 75 mg was given as a deep intramuscular injection to patients on complaint of postoperative pain as a rescue.
The data obtained was analyzed using statistical software SPSS (Statistical Package for Social Sciences) Version 10.0.5. Mean and standard deviation for Visual Analogue Scale (VAS) were estimated from the sample for each study group. Student's "t" test was used to test the significant pain reduction between the Study group and Control group. Fisher's exact test was used to find out the association between various signs and symptoms in the two groups. P < 0.05 was considered as the level of significance.
| Results|| |
The study sample of 25 patients was evaluated and 5 patients did not fit the inclusion criteria and so were eliminated from the study. The remaining patients were divided into 2 matched groups of 10 each.[Table 1]
Patients in Study group had significantly less VAS value than Control Group at all postoperative time intervals(P<0.05) [Table 2]. The values clearly indicate that Study group patients had lesser postoperative pain than Control group patients.
Rescue analgesic was given to 5 (50%) patients in Study group as compared to all 10 patients (100%) in Control group (P=0.167). The time and number of rescue analgesic intake were noted. It was noted that of all 10 patients in the Control group (100%) who required rescue analgesics, 7 patients (70%) required it within the first hour postoperatively and 3 patients (30%) required it within the second postoperative hour. The mean VAS scores at the second hour was 82 for this group indicating very severe pain [Table 2]. They also required a repeat analgesic intake after 8 hours when their mean VAS score was 56 indicating severe pain. In the Study group only 5 patients (50%) required the rescue analgesic .Of this 3 patients (30%) required the rescue analgesic between the eighth and ninth hour postoperatively and 2 patients (20%) required the rescue analgesic between the ninth and tenth hour postoperatively. The mean VAS score of this group at the eighth hour was 28 indicating mild to moderate pain [Table 2]. Thus the Study group patients suffered lesser pain and had a reduced analgesic requirement.
No patients in either group had nausea. No patients complained of gastritis in Study group whereas 60% of the Control group patients had the complaint. No patient had any discomfort due to the numbness [Table 3].
| Discussion|| |
Results suggested post operative pain relief with preincisional peripheral nerve block using 0.25% bupivacaine was better compared to the control group. The study goup showed lesser VAS score and reduction in rescue analgesics.
Long acting anaesthetic like bupivacaine are used for preemptive analgesia  in order to forestall the onset of post operative pain. The pain relief persisted for as long as 40 hrs.
Preemptive analgesia is defined as antinociceptive treatment that prevents establishment of altered central processing of afferent input from injuries. However its value has not yet been clearly proved. The conflicting results in the pre versus post operative infiltration studies, might be due to technical errors such as heterogenous infiltration techniques, different doses and volume of local anaesthetic leading to variable degrees of afferent blockade. This study minimizes these errors by standardizing the peripheral nerve block. A single operator delivered 2ml of 0.25% bupivacaine very close to the nerve bundle supplying the surgical area.
VAS scale is an accepted method of assessing pain in the post operative period , .
The actual time of onset of local anaesthetic action was unable to be clocked because the nerve block was given after the patients were anesthetized and intubated. The incision was made 10 minutes after the block was given.
Prospective case control study is a valid methodological approach . Once the design of the study is completed it is very easy to execute.
No patients reported cardiotoxicity with bupivacaine. Hence it is safe. The long acting local anaesthetic is increasingly finding wide acceptance in oral and maxillofacial surgery. ,,
Administration of diclofenac injections as rescue analgesics was also less in the study group but because of the sample size, it is not statistically significant. (P=0.167)
The comfort level of the patient as shown by VAS score was also far superior in the study group.
This study shows that by some simple peripheral nerve blocks , the post operative period of a patient undergoing faciomaxillary surgery can be made very pleasant and tolerable.
From our study we conclude that preincisional peripheral nerve block with 0.25% bupivacaine is a safe, easily administered and effective method to reduce postoperative pain in oral and maxillofacial surgery.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]
[Table 1], [Table 2], [Table 3]